1. Field of the Invention
The present invention relates to methods for booting a computer, more particularly a computer with a monotask operating system.
2. Discussion of the Related Art
Microcomputers are increasingly used; they can be used with various types of operating systems. The most widespread operating system, for which most of the softwares has been developed, is DOS (Disc Operating System).
There are so-called "multitask" operating systems that allow for simultaneously executing programs and sharing resources, such as the microcomputer's memory, the hard disc, and so forth. The drawback of DOS is that it is monotask, that is, it only allows the execution of one program at a time, all the sharable resources being then assigned to this program only.
Many DOS-operated microcomputers can be connected to a network serviced by a server. The server is generally provided with expensive peripheral devices (plotter, laser printer . . .) that can be used by all the microcomputers connected to the network. The server is also provided with a large-size mass storage device capable of storing a large amount of information and softwares. A microcomputer connected to the network can have its own mass storage device (hard disc) in which a user stores only the programs of the server that he most frequently needs.
In companies where many microcomputers are used, it is often necessary to update information or programs on the microcomputer's hard disc. Updating is too complex a task for an average user; so, an expert has to update each microcomputer through the network or from floppy disks, which is a time consuming and tedious task.
Further, a user often needs to carry out periodical security tasks, such as backups of the hard disc or checking whether viruses are present. Such operations are often time consuming, so the user is inclined to carry out these operations less often than required and thus risks data loss.
If a microcomputer connected to the network uses a multitask operating system, the server can perform updating operations when the microcomputer is on, even when a person is using it. It would even be possible, in that case, to make the server carry out determined tasks in the microcomputer, such as security tasks. However, it is not possible, presently, to make the server execute, at any time, tasks in a microcomputer using a monotask operating system, more particularly if a person is using the microcomputer.
The monotask operating systems have other drawbacks that will appear hereinafter.
When booting a DOS-operated microcomputer, for example, a predetermined number of so-called Terminate and Stay Resident (TSR) programs are loaded in memory. The TSR's to be loaded are listed in startup files referred to as CONFIG.SYS and AUTOEXEC.BAT, locally stored, for example on a hard disc, or provided by a server. A TSR is executed at specific events (a program being executed is then interrupted). Those specific events can be the striking of a determined sequence of keys, moving a mouse, transmitting data from or to a peripheral device . . .
Amongst the various TSR's, there are programs referred to as "drivers" that should necessarily be installed if it is desired to use an associated peripheral device. The role of the driver is generally to intercept and translate the information flowing between a peripheral device and the microcomputer. For example, when keys are pressed, a keyboard driver translates the codes provided by the keyboard into standardized codes corresponding to symbols marked on the keys.
The loaded TSR's occupy memory which, frequently, can be freed only by rebooting the microcomputer. Sometimes, the installation of TSR's leaves insufficient memory to certain programs. Additionally, TSR's may happen to be incompatible one with respect to another and with certain programs. More particularly, the use of a tape backup device is incompatible with some TSR's often installed in a microcomputer.
When such a problem of compatibility with installed TSR's is encountered, it is necessary to cancel the TSR's in the startup file and to reboot the microcomputer. To restore the initial conditions, the cancelled TSR's should be added back in the startup file and the microcomputer rebooted again. If those operations are to be executed each time a security task is to be carried out, especially the hard disc backup, one is also inclined not to carry out this security task as often as necessary.
An object of the invention is to enable the execution of tasks in an initially powered-off computer.
Another object of the invention is to enable a server to operate an initially powered-off computer.